1. Field of the Invention
The present invention relates to an ophthalmic apparatus and more particularly, to an ophthalmic apparatus provided with alignment system to align the apparatus with respect to a predetermined portion in the inside of an eye of an examinee.
2. Description of Related Art
Alignment system in conventional ophthalmic apparatuses is to locate the optical axis of the apparatus coaxially with an examinee's eye, specifically, a visual axis of the eye, and is to position the apparatus so as to provide a predetermined working distance between the same and the eye. Alignment in prior arts would be performed for positioning an apparatus within an acceptable error range to an examinee's eye by assuming the location of the apparatus with respect to the examinee's eye for alignment only.
In the conventional apparatus mentioned above, it is not possible to set a measurement portion (treatment portion) at an optional point in the inside of an examinee's eye. For instance, an apparatus for measuring the extent of opacity of a crystalline lens of an examinee's eye also can not set measurement portions at plural expected points.
If the apparatus is located within an acceptable error range with respect to the examinee's eye, dislocation from a proper point to be measured may be disregarded, and thereby reappearance of the measured portion can not be obtained sufficiently. This can not remove measurement errors caused by difference in measured points. If measurement and observation in a lapse of time at an optional point are carried out through the apparatus, obtained data tend to be greatly short of the reliability.